In addressing sleep related problems, such as sleep apnea, insomnia and other physiologic events or conditions occurring during sleep, various hospitals and clinics have established laboratories, sometimes referred to as “Sleep Laboratories” (sleep labs). At these sleep labs, using instrumentation, such as patient bio-data sensors connected to a polysomnograph (PSG) machine, a patient's sleep patterns may be monitored and recorded for later analysis so that a proper diagnosis may be made and a therapy prescribed. Varieties of sensors have been devised for providing recordable signals related to respiratory (inhaling and exhaling) patterns during sleep. These sensors commonly are mechanical to electrical transducers that produce an electrical signal related to respiration.
The current sleep lab accreditation guidelines, as per the American Academy of Sleep Medicine (AASM), use two different sensing systems at the same time on the same patient to measure respiratory air temperature and respiratory air pressure changes. Respiratory air temperature fluctuations (changes) can be measured using either a thermocouple or a thermistor attached directly to a sleep lab's PSG machine. Respiratory air pressure fluctuations (changes) are can be measured using a nasal pressure prong cannula placed in the patient's nostrils and attached, via a plastic hose, to an air pressure transducer. The output of air pressure transducer connects directly to the PSG machine.
Air pressure transducers with nasal cannulas in combination with either a thermistor or thermocouple, as used in sleep studies, are invasive, uncomfortable and prone to clogging and body movement and, thus, put an unnecessary strain and discomfort on patients.